The invention relates to a reaping or haying machine comprising at least one rotatingly drivable mowing or raking unit which is provided with implements constructed as mowing blades or as raking tines and defining a working plane and by means of a compensating means is supported on a support frame connectable to a tractor pivotally about a pivot axis extending transversely of the travelling direction.
Agricultural machines of this type are known in a large number of different configurations. The mowing or raking units are attached to or installed on a tractor. To enable an adaptation to the particular terrain profile in operation, the mowing or raking unit to which the working implements are attached is supported articulately at the tractor at a relatively great height in pronounced cantilever manner. Pitch movements occurring due to braking, accelerating or travelling over uneven ground have disadvantageous effects on the working result and the mowing or raking unit because the latter can be forced into an unfavourable position by the tractor. This leads to high moments about a transverse axis; said moments are further intensified by the high articulation on the tractor and for example in machines with a three-wheel or four-wheel chassis can lead to the front wheels being more highly loaded than the rear wheels. This applies analogously also to mowing or raking units provided with a slide plate.
The result of this is that the mowing or raking units, in particular the working implements attached thereto exhibit the tendency to penetrate into the ground more at the front. This leads to damage to the grass sod and soiling of the crop with soil particles. Also, the working implements may be deformed and break. Moreover, ground contacts can lead to load peaks and as a result also damage to the machine; greater wear and a higher power requirement are usually inevitable.
This problem cannot be solved by strengthening the construction. Apart from the greater costs, a heavier construction would have the disadvantage of poor manoeuvrability of the combination and a further increase in the power requirement without improving the operating performance. Also, no increase of the travelling speed and the working width is possible.
The problem underlying the invention is therefore to provide a mowing or haying machine of the aforementioned type in which the known disadvantages are obviated. Thus, the tools should be able to be adapted in easily moving and rapid reaction at the intended working height to the particular ground profile over the entire working width. The motions of the tractor or a separate associated vehicle are not to be imparted to the mowing or raking units; on the contrary, the mowing or raking units are to be able to execute their own motions and follow the terrain profile so that the resistance to travel and the machine load are kept low and damage of the grass sod as well as damage to the working implements and soiling of the crop are to be largely avoided. The support area or the wheels of the mowing or raking unit are accordingly always to run parallel to the ground surface and ground irregularities are to be easily compensatable without pitch movements of the towing vehicle or the chassis being able to have disadvantageous effects. The constructional expenditure necessary for this is to be kept small but nevertheless a high operational reliability is to be guaranteed. It is also to be possible to easily overcome suddenly occurring obstructions.